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429d2e8342
On p8 systems, with relocation on exception feature enabled we are seeing kdump kernel hang at interrupt vector 0xc*4400. The reason is, with this feature enabled, exception are raised with MMU (IR=DR=1) ON with the default offset of 0xc*4000. Since exception is raised in virtual mode it requires the vector region to be executable without which it fails to fetch and execute instruction at 0xc*4xxx. For default kernel since kernel is loaded at real 0, the htab mappings sets the entire kernel text region executable. But for relocatable kernel (e.g. kdump case) we only copy interrupt vectors down to real 0 and never marked that region as executable because in p7 and below we always get exception in real mode. This patch fixes this issue by marking htab mapping range as executable that overlaps with the interrupt vector region for relocatable kernel. Thanks to Ben who helped me to debug this issue and find the root cause. Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
56 lines
1.2 KiB
C
56 lines
1.2 KiB
C
#ifndef _ASM_POWERPC_SECTIONS_H
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#define _ASM_POWERPC_SECTIONS_H
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#ifdef __KERNEL__
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#include <linux/elf.h>
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#include <linux/uaccess.h>
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#include <asm-generic/sections.h>
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#ifdef __powerpc64__
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extern char __start_interrupts[];
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extern char __end_interrupts[];
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extern char __prom_init_toc_start[];
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extern char __prom_init_toc_end[];
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static inline int in_kernel_text(unsigned long addr)
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{
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if (addr >= (unsigned long)_stext && addr < (unsigned long)__init_end)
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return 1;
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return 0;
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}
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static inline int overlaps_interrupt_vector_text(unsigned long start,
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unsigned long end)
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{
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unsigned long real_start, real_end;
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real_start = __start_interrupts - _stext;
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real_end = __end_interrupts - _stext;
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return start < (unsigned long)__va(real_end) &&
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(unsigned long)__va(real_start) < end;
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}
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static inline int overlaps_kernel_text(unsigned long start, unsigned long end)
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{
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return start < (unsigned long)__init_end &&
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(unsigned long)_stext < end;
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}
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#undef dereference_function_descriptor
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static inline void *dereference_function_descriptor(void *ptr)
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{
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struct ppc64_opd_entry *desc = ptr;
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void *p;
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if (!probe_kernel_address(&desc->funcaddr, p))
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ptr = p;
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return ptr;
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}
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#endif
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#endif /* __KERNEL__ */
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#endif /* _ASM_POWERPC_SECTIONS_H */
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